Acid treated polyether polyurethane foam end wrap

ABSTRACT

A superior end wrap comprising a particular type of open-celled polyurethane foam of specified porosity and thickness which foam has been treated with weak carboxylic acids. Also disclosed is a permanent waving process using said acid treated end wraps.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to acid treated polyurethane foam end wraps foruse in the cold permanent waving of hair. Further, the invention relatesto the process of using the treated end wraps in cold permanent waving.

2. Prior Art

Cold permanent waving of hair has been a popular means of waving hairfor a number of years. This popularity is due to the greater conveniencefor this method over other methods where externally applied heat isneeded to achieve the desired result. This additional convenience haspermitted nonprofessional consumers to wave their hair in their ownhomes. In cold waving, the waving is accomplished by applying a reducingagent to the hair which causes the hair to be "softened" (the disulfidelinkages present in the keratin of hair are broken). This reducing stepmay be done after the hair has been sectioned into individual tressesbut before it has been rolled onto curlers, after the rolling has beenaccomplished or at both times. After sufficient time has elapsed thehair is rinsed and neutralized by chemical or air oxidation, which stepreforms the disulfide linkages broken in the aforementioned reducingstep.

Cold permanent waving is not without its problems however. The materialsare oftentimes somewhat difficult to use with the desired result notalways achieved. For example, the ends of the hair present particularproblems from a handling point of view, as well as from a hair damagepoint of view. In the waving process, the free ends of the hair must bewound about a cylindrical body (a curler) and this presents somedifficulty. To overcome this problem most commercial waving kits containsmall square or rectangular pieces of paper or other material (endwraps) which are folded and placed around a hair tress in such a mannerthat they embrace the free end of the tress.

Among the types of materials which have been used for the end wrap arepermeable polyester and polyether polyurethanes as disclosed by Haefelein U.S. Pat. No. 3,345,993, issued Oct. 10, 1967; impermeable polyesterand polyether polyurethane as disclosed by Haefele in U.S. Pat. No.3,465,759, issued Sept. 9, 1969; and paper as disclosed by Bonilla inU.S. Pat. No. 2,991,790, issued July 11, 1961. Of these materials,permeable polyurethane foams prepared by condensation of organicisocyanates with polyols are especially useful. Such polyurethanes haveexcellent solvent resistance, and color stability in the presence ofultraviolet light.

All of these types of end wraps which have been disclosed in the priorart are well known to be helpful in the winding process. However, theydo not fully protect the ends of the hair. The desirability ofprotecting the ends of the hair in permanent waving stems from the factthat repeated use of conventional waving procedures is often accompaniedby an overexposure of the hair ends which are susceptible to damagebecause of the age of the hair at the ends and the stress the ends areexpose to during the winding process. Such ends, when subjected torenewed cold waving treatments, generally exhibit undue frizziness,curling, harshness and dryness because frequent treatment is believed tounduly stress and overexpose the hair ends in renewing or repeating thewaving process.

There have been attempts in the past to treat certain types of end wrapswith chemical agents so that the waving solution is counteracted beforereaching the hair ends (See, for example, the aforementioned Bonillareference). Also included in some prior art attempts was the treatmentof paper end wraps with citric acid to counteract the waving solutionand thereby protect hair ends.

While it would be highly desirable to treat end wraps of the preferredpolyurethane materials with waving solution counteractant, certain ofsuch common counteractant chemicals are not compatible with all types ofend wrap polyurethane. Some agents such as citric acid, for example,tend to degrade and discolor polyester polyurethane. The concurrentlyfiled application of Adrion and Hartsough having Ser. No. 670,594 isdirected toward particular preferred acid treated polyester polyurethaneend wraps. There is, however, a continuing need to identify and selectcompatible materials for use in realizing preferred treated end wrapsfor cold permanent waving products and methods.

Accordingly, it is an object of this invention to provide effective acidtreated end wraps which are useful in the keratin modification process.

It is a further object of this invention to provide such treated endwraps which are made with preferred compatible end wrap and acidtreatment materials.

It is a further object to provide an improved method for permanentlywaving hair by utilizing treated end wraps made from preferredmaterials.

It has been surprisingly discovered that by selecting polyetherpolyurethane end wraps for treatment with weak carboxylic acids, theabove objectives can be realized and end wraps prepared which aresuperior to similar articles of the prior art.

SUMMARY OF THE INVENTION

The present invention is directed to end wraps for use in permanentwaving processes. The end wraps comprise permeable flexible wafers ofopen-celled polyether polyurethane foam containing a solid, weakcarboxylic acid to the extent of at least 5 milligrams of acid per cubicinch of foam.

The foam wafers have a thickness ranging from about 1/16 inch to about1/64 inch and an average pore incidence of from about 30 to about 120pores per linear inch. The carboxylic acid has a pK₁ between about 2.5and about 6.0.

The present invention is also directed to a process for imparting apermanent wave to hair. Such a process comprises the steps of formingthe hair into tresses, wrapping about the end of each tress a flexible,acid-treated end wrap of the type decided above, winding each tress on acylindrical body, saturating each wound tress with a keratin-reducingcomposition and thereafter neutralizing the action on the hair of saidkeratin reducing composition.

DETAILED DESCRIPTION OF THE INVENTION

The present invention resides in the discovery of an improved end wrapcomprising a particular type of porous polyether polyurethane foam wafertreated with a carboxylic acid.

POLYETHER POLYURETHANE FOAM END WRAP MATERIAL

The polyurethane foam material used for the end wrap wafer in theinvention herein can be characterized as "polyether polyurethane."Polyurethanes are, of course, prepared by condensing polyols withorganic isocyanates. Polyurethane foams are divided into two majorcategories depending on the type of polyol used in preparation -- either"polyether" polyols or "polyester" polyols. The "polyether" foams arethe materials utilized in this invention. These polyurethane foams canbe prepared by a variety of methods which are well known in the art.Essentially, such foams are made by the condensation of organicisocyanates, such as tolylene diisocyanate, with polyethers such as thereaction product of propylene oxide and glycerol in the presence of acatalyst, surfactant and perhaps a blowing agent. Basic apparatus,processes and starting materials for preparing such polyetherpolyurethane foams are disclosed, for example, in Hoppe et al, U.S. Pat.No. 2,764,565; issued Sept. 25, 1956; Lamplugh et al; U.S. Pat. No.3,772,218; issued Nov. 13, 1973; Lamplugh et al, U.S. Pat. No.3,799,898; issued Mar. 26, 1974; Fishbein et al; U.S. Pat. No.3,879,316; issued Apr. 22, 1975 and Ridenour et al; U.S. Pat. No.3,880,780; issued Apr. 29, 1975. All of these patents are incorporatedherein by reference. For purposes of this invention a polyetherpolyurethane refers to a polyurethane made from a polyether polyol andan organic isocyanate.

The polyether polyurethane foam end wraps used as the starting materialfor this invention are the polyether analogs of the polyesterpolyurethane exemplified in U.S. Pat. No. 3,345,993, Oct. 10, 1967, toHaefele incorporated herein by reference. These end wraps are preferablyeither square or rectangular in shape and have dimensions within therange from 13/8 inches to 13/8 inches to 4 inches × 4 inches. Anespecially preferred size and configuration is a rectangular waferhaving the dimensions 3 inches × 2 inches.

The thickness of the untreated foam end wraps can vary within the rangeof 1/64 inch to 1/16 inch. As the length and width are increased, athinner end wrap should be used. Foam end wraps which are thinner thanabout 1/64 inch are difficult to process and do not have sufficient tearstrength for the intended use. End wraps having thicknesses greater thanabout 1/16 inch yield too large a curl. The preferred thickness for thepurpose of this invention is 1/32 inch.

The degree of porosity of the end wrap must be sufficient to permitsubstantially unimpeded flow of the waving and neutralizing solutions.An average pore incidence from about 30 to about 120 pores per linearinch is necessary for adequate flow. More numerous pores are preferablein the case of thinner end wraps. The preferred end wraps have anaverage of about 80 pores per linear inch.

ACID TREATMENT MATERIAL

The polyether polyurethane foam end wraps are treated with an acidicmaterial to counteract the effects on hair ends of the keratin-modifyingsolution. The acid with which the foam end wraps of this invention aretreated can be any solid, weak, carboxylic acid having a pK₁ varyingbetween about 2.5 and 6. The acid utilized must have pK₁ characteristicswithin these ranges to insure that the integrity of the polyetherpolyurethane foam is not impaired. The pK₁ value should be less thanabout 6 so excessive amounts of the acid need not be used. As usedherein an acid is "solid" if it is in solid form at room temperature,i.e. 20° C.

Examples of suitable carboxylic acids are succinic, itaconic, adipic,azelaic, suberic, pimelic, benzoic, fumaric, o-phthalic, citric, malic,glutaric, p-amino benzoic, ascorbic, furoic, gallic, hippuric, maleic,mendelic, mesaconic, methylglutaric and methylsuccinic acids. Apreferred group of carboxylic acids includes citric, glutaric and malicacids. The most preferred acid is citric acid.

It has been found that the amount of acid present in the foam end wrapsof this invention can vary depending on the thickness and outsidesurface area of the wrap, but a minimum level of 5 milligrams ofacid/cubic inch of foam is thought to be required to ensure thatprotection is obtained. It is preferred, however, that the amount ofacid present be from about 9.0 milligrams to about 300 milligrams percubic inch of foam. This range allows the ends of the hair to beadequately protected while still ensuring that they receive some wave.

END WRAP PREPARATION

The foam end wrap material may be conveniently treated by use of a watersolution of the acid. The material may be passed through the watersolution, or the solution may be brushed or sprayed onto the material.The treated material is then dried by means of a drum dryer or oven, airexposure or by other suitable means to remove the moisture present. Theconcentration of acid in the water solution depends on the acid used,the method of application employed and the acid concentration desired inthe treated foam end wraps. The concentration of acid typically would bein the range of about 0.2% to about 60%.

To decrease the likelihood of the end wraps picking up static charge,the foam may be treated with an antistatic material such as a mineraloil mixture.

HAIR WAVING METHOD

A preferred embodiment of this invention relates to the process of coldpermanent waving. Use of this invention's acid treated foam end wraps inthe same manner as conventional end wraps in cold permanent wavingreduces the strength of the wave given to the ends of the hair. This isbelieved to be due to the lowering of the pH of the reducing solutionwhen it comes into contact with the treated foam end wrap which isaround the ends of the hair. This results in a softer looking wave, withgreater fullness, but with the same strength of curl as current productsgive except at the hair tips.

More specifically, in regard to the aspect of cold permanent wavingprocesses, this invention comprises the steps of forming the hair intotresses, wrapping around the end of each tress a treated foam end wrapof the type disclosed herein, winding each tress about a cylindricalbody, i.e., a curler, saturating each tress with a keratin-reducingcomposition and thereafter neutralizing the action on the hair of saidkeratin-reducing composition. Alternatively, the keratin-reducingcomposition is applied to the hair both before and after the hair isrolled upon curlers.

The keratin-reducing compositions which may be used in the permanentwave processes of this invention contain a water-soluble nonvolatilemercaptan such as mercapto-alkanoic acids, mercapto-acetic acid,mercapto-propionic acid, mercapto-butyric acid and water-soluble saltsthereof. Examples of other suitable mercaptans are thioglycolic acid,sodium thioglycolate, potassium thioglycolate, monoethanolaminethioglycolate, β-mercapto isobutyric acid, thiohydracrylic acid,β-mercapto-n-butyric acid, mercapto-caproic acid, thioglycerol andthiolactic acid. These compositions have a pH of 7.0 to 9.5 which can beprovided with alkaline agents such as ammonia, monoethanolamine,diisopropylamine, sodium hydroxide, potassium hydroxide and the like.

In addition to the mercaptans, it is often desirable, but not essential,to include in the keratin-reducing composition a water-soluble disulfideof the mercaptan used such as dithiodiglycolic acid, dithiodilacticacid, the disulfides of β-mercaptobutyric acid, β-mercaptoisobutyricacid, dithiodihydracrylic acid or a water-soluble salt of these acids toprotect against excessive reduction and damage to the hair in accordancewith the disclosures in U.S. Pat. No. 2,719,814, Oct. 4, 1955, toHaefele and U.S. Pat. No. 2,719,815, Oct. 4, 1955, to Sanders.

The permanent waving processes of this invention can also be used toadvantage in conjunction with pressurized hair waving compositions whichare applied to the hair as a fast-breaking foam. Examples of suchcompositions are disclosed by Banker et al. in U.S. Pat. No. 3,099,603,July 30, 1963, and Sheperd et al. in U.S. Pat. No. 3,103,468, Sept. 10,1963.

The action on the hair of the keratin-reducing compositions can beneutralized by chemical compounds such as bromates, perborates, hydrogenperoxide or the action of air alone.

END WRAP EXEMPLIFICATION

Certain particular embodiments of the invention are illustrated in thefollowing examples but the invention is not intended to be limitedthereto. All percentages used herein previously and subsequently are byweight unless otherwise indicated.

EXAMPLE I

A polyurethane-forming reaction mixture of the following composition isprepared:

    ______________________________________                                        Component                Parts by Weight                                      ______________________________________                                        PROPYLAN 555* Polyether Triol                                                                             100                                               C-6**Catalyst               0.6                                               N-Ethylmorpholine Catalyst  0.1                                               Water                       3.0                                               Tolylene Diisocyanate       31.6                                               (80:20 Mixtures of 2,4- and 2,6-isomers                                      L-532*** Surfactant         3.0                                               ______________________________________                                         *Condensation product of propylene oxide and ethylene oxide with glycerol     (60% - 70% terminal hydroxyl groups; Molecular weight = 5000)                 **Solution of one part (wt.) stannous octoate and two parts (wt.)             dioctylphthalate - Witco                                                      ***Polyoxyalkylene-siloxane copolymer - Union Carbide                    

The above mixture is hand mixed at room temperature and is poured intoan aluminum mold provided with a clamped lid. The mixture is maintainedwithin the temperature range of 140° - 150° F. Foaming is complete inabout three minutes. The resulting foam is allowed to cure at ambienttemperature.

The product is a slab of flexible polyether polyurethane foam of 2.3pounds per cubic foot density, having an average of 60 cells per linearinch. The slab is then cut into 3 × 2 inch wafers or larger sheetshaving a thickness of 1/32 inch.

The reactants and conditions as identified above can be varied inaccordance with the teachings of Hoppe et al, U.S. Pat. No. 2,764,565,issued Sept. 25, 1956 and Lamplugh al, U.S. Pat. No. 3,799,898; issuedMar. 26, 1974, to yield foams having an average of 40, 80 and 120 poresper linear inch and thicknesses of 1/16 and 1/64 inch.

EXAMPLE II

Foam end wraps measuring 3 × 2 × 1/32 inches made according to Example Iwere dipped into a 1% aqueous solution of citric acid (pK₁ = 3.14). Theamount of solution absorbed by each foam end wrap was 1.0 gram(corresponding to about 53 milligrams of acid/cubic inch of foam). Thewraps were then allowed to air dry for a period of about 16 hours atroom temperature (˜ 75° F.).

EXAMPLE III

A sheet of polyether polyurethane foam measuring 153/4 × 183/4 × 1/32inches made according to Example I was dipped into a 6.25% aqueous malicacid (pK₁ = 3.40) solution. The sheet was wrung out until 8.0 grams(corresponding to about 55 milligrams of acid/cubic inch of foam) of thesolution were still retained. The sheet was then let air dry for aperiod of about four hours at room temperature (˜ 75° F). As a finalstep, individual end wraps measuring 3 × 2 × 1/32 inches were cut fromthe sheet.

Substantially similar acid treated polyether polyurethane end wraps arerealized when in the above Example II preparation, the malic acid isreplaced with an equivalent amount of

itaconic acid (pK₁ = 3.85),

adipic acid (pK₁ = 4.43),

azelaic acid (pK₁ = 4.53),

suberic acid (pK₁ = 4.52),

pimelic acid (pK₁ = 4.71),

benzoic acid (pK = 4.19),

fumaric acid (pK₁ = 3.03),

mesaconic acid (pK₁ = 3.09),

o-phthalic acid (pK₁ = 2.89),

citric acid (pK₁ = 3.14),

glutaric acid (pK₁ = 4.31),

p-amino benzoic acid (pK = 4.65),

ascorbic acid (pK₁ = 4.17), or

succinic acid (pK₁ = 4.16).

EXAMPLE IV

The acid treated foam end wraps as prepared in accordance with ExampleII are employed in a permanent waving process using the followingkeratin-reducing composition

    ______________________________________                                        Component              Weight %                                               ______________________________________                                        Monoethanolamine thioglycolate                                                                       11.41                                                  Hydrogen peroxide      0.34                                                   Monoethanolamine       2.30                                                   Mineral oil            1.555                                                  Oleic acid             0.337                                                  Potassium hydroxide    0.088                                                  Ethylene glycol        0.199                                                  Perfume                0.50                                                   Polyoxyethylene (23) lauryl ether                                                                    1.043                                                  Color                  0.10                                                   Distilled water        82.128                                                                        100.000                                                ______________________________________                                    

The hair is washed and separated into tresses. The acid treated end wrapis folded over the wet hair tress so that it covers all of the freeends. Each wrapped tress is then wound upon a curler and secured. Thekeratin-reducing composition is applied to the wound tresses and afterwaiting 15 minutes, rinsed with water and blotted. The head is thencovered with a towel and after an additional 30 minutes the hair isneutralized with a 3% hydrogen peroxide solution. The hair is removedfrom the curlers, again rinsed with water, set in a normal fashion anddried.

The ends of the hair are protected from the total effect of thekeratin-reducing composition by the acid treated end wraps.

What is claimed is:
 1. An end wrap for use in the permanent wavingprocess which comprises a permeable flexible wafer of open-celledpolyether polyurethane foam having a thickness of from about 1/16 inchto about 1/64 inch, an average pore incidence within the range of fromabout 30 to 120 pores per linear inch and, contained in said end wrap, asolid, carboxylic acid having a pK₁ of from about 2.5 to about 6.0, saidacid being present at a level of at least 5 milligrams of acid per cubicinch of foam.
 2. An end wrap according to claim 1 wherein the wafer ofpolyether polyurethane foam has a thickness of 1/32 inch.
 3. An end wrapaccording to claim 1 wherein the wafer of polyether polyurethane foamhas an average pore incidence of 80 pores per linear inch.
 4. An endwrap according to claim 1 wherein the carboxylic acid is selected fromthe group of acids consisting of succinic, adipic, itaconic, suberic,azelaic, pimelic, benzoic, fumaric, o-phthalic, citric, malic, glutaric,p-amino benzoic, ascorbic, furoic, gallic, hippuric, maleic, mendelic,mesaconic, methylglutaric and methylsuccinic acids.
 5. An end wrapaccording to claim 4 wherein carboxylic acid is selected from the groupsconsisting of citric, glutaric and malic acids and the amount of acidcontained in said end wrap is from about 9 to about 300 milligrams/cubicinch of end wrap.
 6. The process of imparting a permanent wave to hairwhich comprises the steps of forming the hair into tresses, wrappingabout the end of each tress a permeable, flexible wafer of polyetherpolyurethane foam having a thickness of from about 1/16 inch to about1/64 inch, said wafer containing a solid, weak, carboxylic acid having apK₁ of from about 2.5 to about 6.0, said acid being present at a levelof at least 5 milligrams of acid per cubic inch of wafer, winding eachtress on a cylindrical body, saturating each wound tress with akeratin-reducing composition and thereafter neutralizing the action onthe hair of said keratin-reducing composition.
 7. A process according toclaim 6 wherein the wafer of polyether polyurethane foam has a thicknessof 1/32 inch and an average pore incidence of 80 pores per linear inch.8. A process according to claim 6 wherein carboxylic acid is selectedfrom the group of acids consisting of citric, glutaric and malic acids.9. A process according to claim 6 wherein the carboxylic acid is citricacid and the amount of said acid contained in said wafer is from about 9to about 300 milligrams/cubic inch of wafer.